In the past, scholars could gather in coffee houses
and talk about the latest scientific or mathematical discoveries. The goal of Scientific Clearing House is to provide a venue for such discourse.

Thursday, September 28, 2006

A new global fixed point

James Lovelock's most recent book - The Ages of Gaia, argues that the earth is headed for a new fixed point at a much elevated temperature. He cites several mechanisms that are providing positive feedback to rising temperatures. One example is the emission of dimethylsulfide (DMS) by ocean phytoplankton into the atmosphere. DMS is what makes the ocean smell like well the ocean. DMS also contributes to cloud cover which increases the albedo of the earth. For small temperature increases and increases in UV radiation, phytoplankton upregulate DMS release and provide negative feedback However, recent evidence (I must admit that I haven't checked the primary source) suggests that for a very large increase in temperature, DMS release may actually decrease and lead to positive feedback. Lovelock also believes that the increased global temperatures will turn the Amazon rain forest into a savannah leading to even less carbon sequestration. Studies in the UK have found that as temperatures increase, CO2 is being released from the ground at a higher rate. Aquatic cyanobacteria (also known as blue-green algae), which are photosynthetic and may be the largest carbon sink we have, may also down regulate CO2 intake with increasing temperatures. The bottom line is that relying on Gaia to provide negative feedback to our fossil fuel use may not be a viable option. The earth may transition to a new fixed point where the temperature may be as much as 10 degrees warmer. This could turn much of the currently temperate zones into deserts. Lovelock believes it will end civilization as we know it. Even I think this is probably an overly bleak prediction but it is definitely something to think about.

Excited to see you posting again. I am curious about where the estimation of the fixed point comes from. From your synopsis, it almost sounds like the research might suggest that earth's temperature could turn into a form of feed-forward process. Is there some other negative feedback mechanism that wasn't mentioned?

The new fixed point is a conjecture of course by Lovelock. Eventually, some negative feedback effects will counter the positive feedback. He believes the new fixed point is say 10 degrees higher but we could end up like Venus and be hundreds of degrees higher.

I think I heard the Venus comment (which is not based on science, just an existence proof of how hot things can get) in a podcast of the Science Show (from Australia), last month. I don't have a specific reference to this I'm afraid.